Pippa Bennett-Warner
From Tardis Wiki, the free Doctor Who reference
Pippa Bennett-Warner played Saibra in the Doctor Who television story Time Heist. She later read Helana and the Beast for Time Lord Fairy Tales and Bill and the Three Jackets for The Day She Saved the Doctor, as well as voicing O and the Deterrent in The Diary of River Song: Series Three for Big Finish Productions and Livia in Gallifrey: Time War box sets.
